JPH02115421A - Work machine control method for construction machine - Google Patents

Abstract

PURPOSE:To eliminate a shock, cavitation and an operation delay, and ensure the smooth motion of a work machine by actuating an operation valve and a pump variable device via a controller and avoiding the occurrence of linear drive hydraulic pressure. CONSTITUTION:The operation valve 7 and pump variable device of a hydraulic piping system are constituted with a hydraulic control valve and pump driven with a controller 5. In addition, an electric operation lever 1 is operated and a signal is sent to the controller 3 from a manual setting switch 4 selected by an operator depending upon a job condition, or a mode selector switch for automatically setting a work mode depending upon a job condition for operating the controller 5, thereby quickening and slowing the operation of the valve 7 and an oil pump 6. Furthermore, circuit pressure does not rise at a constant ratio with the elapse of time and modulation function is made at a ratio in multiple steps. Also, the shock of operation, the cavitation of the oil pump 6 and the operation delay thereof are prevented.

Description

[Detailed Description of the Invention] Industrial Field of Application: The present invention is applicable to the following:
The present invention relates to a control method for construction machinery including modulation, which enables various operations without drive shock by avoiding the generation of linear drive oil pressure.

BACKGROUND OF THE INVENTION Large construction machines such as power shovels, shovel dozers, and bulldozers are equipped with working machines adapted to various types of work, and are mainly driven by hydraulic drive. Hydraulic movement involves pumping pressure oil pressurized by a plunger pump to the upper or lower side of the piston of a hydraulic cylinder, and movement of the work equipment connected to the piston rod of the hydraulic cylinder. The lever moves the spool of the operating valve in the pressure oil piping system to switch and control the flow of pressure oil. The hydraulic piping system includes a pressure regulating valve that prevents pressure oil from reaching an excessively high pressure, a backflow prevention valve that prevents backflow when the circuit pressure of the pressure oil that was driving the work equipment is lost, and a hydraulic cylinder. A vacuum prevention valve is also installed to prevent a vacuum from forming inside.

When using such a hydraulic drive mechanism to move a working machine or the like installed in a construction machine, it is not possible to freely change the operating speed of a hydraulic valve, typified by an operating valve, and a variable pump device.

Problem to be solved: In conventional hydraulic systems, valves are operated at a constant speed, so hydraulic input and output are applied linearly, which poses various operational difficulties. .

In other words, when the valve operates quickly, a shock occurs when the work machine is started or stopped. If the valve operates slowly, there will be a delay in operation when starting and stopping the work equipment. Furthermore, when the same work equipment has an operation pattern that allows the speed to be changed in two or more ways, for example, when it has an excavation mode (normal speed mode) and leveling mode (1/2 speed mode), or a high travel mode and a low travel mode. Moreover, it was inevitable that one mode would cause a large shock during activation, and the other mode would cause a delay in activation. Additionally, when the pump variable device was activated quickly, cavitation occurred in the circuit in addition to shock.

Means for Solving the Problems: The method of the present invention has solved the above problems by installing a controller and operating the operating valve and pump variable device via the controller. With this control method, it is possible to prevent the operating states of valves and pump variable devices from changing instantaneously, and it is possible to provide a time range for the expression of driving force to the work equipment, etc., and to ensure smooth operation without shock or cavitation. It became possible to perform various exercises. Control by the controller can be easily accomplished electrically.

Structure and operation of the invention: In the method of the present invention, a controller operates operating valves and pump variable devices of a hydraulic piping system that drive construction machines such as power shovels, shovel dozers, and bulldozers, or move working machines equipped on these machines. Hydraulic control valve and pump. The controller operates the valves and pumps to achieve a predetermined modulation by operating an electric lever by the operator, automatically controlling one of several modes selected by the operator or preset according to the work situation. let

The modulation of valve actuation is illustrated in the illustration of FIG. This input is a typical setting example in which the stroke increase from the start of the valve and pump variable device operation (when the stroke is Iflin) until reaching the full stroke is represented by straight lines a and b at a constant rate with respect to time. In the conventional example, the system delay is added to the signal.
The answer is yes.

This stroke is closely related to circuit pressure, and at full stroke, the circuit pressure is max.

In the pulp operating state in the method of the present invention, the rate at which the stroke changes over time is multi-stage, and modulation patterns A, B, etc. shown by bent lines are set, and the settings are used depending on the conditions. . If the setting modulation is A for input signal a, the output increases according to the setting of A. If the set modulation is A with respect to the input signal, b is input later than A, so the output remains b, and it operates slowly so that no delay is felt during operation. When the input signal is set to modulation B, the output increases according to the setting of B because b is input earlier than B.

Similarly, when the pressure is reduced from a full stroke, the valve is delayed when the input signal is straight line 2 in the conventional example, but in the method of the present invention, the valve is in the operating state represented by the modulation pattern Z. Therefore, for signal inputs a, b, or 2 that are linear changes at a constant rate, modulation patterns A, B, or Z are such that the stroke does not occur earlier than the set time.

That is, the method of the present invention, when moving a construction machine or an equipped working machine by hydraulic drive: Hydraulic control that operates the operating valve and pump variable device of the hydraulic piping system via a controller operated by an electric lever. Valves and pumps: those in which the operating valves and pumps raise and lower the pressure oil circuit pressure and pump discharge volume, and the ratio between the operating time and the corresponding rise and fall and increase and decrease is not constant, and changes sequentially in multiple stages. A command is issued from the controller so that: When the pressure oil circuit pressure rises and falls at a constant rate according to the operating time, the operating valve and pump variable device operate to prevent it from moving faster than the set time. It is designed to perform a modulation effect to absorb the shock that occurs when operating valves and pumps, enabling smooth valve operation and pump control, and also prevents cavitation in the circuit. . Furthermore, the modulation pattern can be arbitrarily used in a plurality of modes by instructing the controller to set it manually or automatically depending on the working state. In addition, when the construction machine is running, the valves are operated with suitable modulation, thereby enabling shock-free running at all speeds.

Example: A specific embodiment of the present invention will be described below.

For example, if a construction machine is equipped with crawlers and can freely move forward, backward, and turn, and is equipped with work equipment such as packet, tilt, and swivel functions, the hydraulic system is is provided. The hydraulic drive is pressurized by an oil pump driven by the engine of the construction machine.
The pressure oil flow path is selected by valve operation and the work equipment moves. In the conventional technology, the spool of the control valve was operated only by the work equipment control lever operated by the operator, whereas in the present invention, the controller is controlled by an electric lever, and the operation of the control valve and pump control device is maintained at a slow speed. ing. the result,
The circuit pressure of the pressure oil does not rise or fall at a constant rate over time, but instead performs a modulation effect represented by a bent line at a multi-stage ratio.

Signals are sent to the controller from a manual setting switch that is selected by the operator depending on the state of work, and a mode changeover switch that automatically sets the work mode depending on the conditions.

As a result, it is possible to have multiple modulation effects that correspond to a variety of tasks.

Next, the working conditions and modulation effect settings will be explained. What is shown in FIG. 2 has three sets of valve operation modulations (the method of the invention has at least two sets).
This is an example.

In this case, the broken lines a, b, and cSz all indicate the state when the operating lever is operated.

a is sudden operation, b is normal operation, C is slow operation, 2 is a
This is an operation with a similar tendency. Among these, in the ascending modes a and b (the descending mode 2), the occurrence of a shock during operation is unavoidable. This is clearly seen in the mode a, which tends to make a full stroke sometimes instantaneously. Note that in the slow operation of C, the upward movement to reach the full stroke is inherently slow, so no shock is felt, and the lever operation represented by C can substantially be the modulation pattern C.

Modulation patterns corresponding to these can be set automatically according to each work mode, or can be obtained by instructing the controller through manual settings by an operator, and then issuing commands from the controller to the operating valve and pump variable device section. Modulation pattern A illustrated in Figure 2
Regarding B and B, if we take the working mode of a power shovel as an example, modulation pattern B is suitable for heavy excavation because it has no shock and soft behavior, and there is no delay in accuracy for straightening. A modulation pattern without A is suitable. Furthermore, when driving, modulation pattern A with no delay is preferable at low speeds, and modulation pattern B with less shock is preferable at high speeds because it is less affected by inertia.

In formulating the modulation pattern in the present invention, the initial or final no-effect band (dead band) of the operation of the operation valve or the operation of the pump's variable device is quickly passed through, and the circuit pressure rises to ensure sufficient operation effect. is obtained (in this example, approximately 30% of the middle zone of the stroke)
) maintains a tendency to operate slowly. These formulations can be controlled by operating an electric lever by incorporating an arithmetic circuit and a modulation selection command circuit into the controller.

Effects of the Invention: When the method of the present invention is used, it is possible to effectively prevent shocks when the construction machine is running and when the working machine is started and stopped, and cavitation of the pump can also be suppressed. By selecting a modulation pattern according to the work mode, it can be adapted to work that requires precision without delaying operation, or work that does not require precision but requires rapid progress without causing shock. It has become possible.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of a specific embodiment of the method of the present invention, and FIG. 2 is an explanatory diagram of a modulation pattern of an operating valve and a pump based on commands from a controller. Fu' shellfish! 'j'L' Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. When hydraulically driving construction machinery or moving the installed work equipment: Hydraulic pressure that operates the operating valves and variable pumps of the hydraulic piping system via a controller operated by an electric lever. For control valves and pumps; when the operating valve raises and lowers the circuit pressure of pressure oil and increases and decreases the pump discharge volume, the ratio between the operating time and the corresponding rise and fall and increase and decrease is not constant, but changes sequentially in multiple stages. When the pressure oil circuit pressure rises and falls at a constant rate according to the operating time, the control valve and pump variable device operate so that it does not move faster than the set time. A method for controlling a working machine for construction machinery, characterized in that: the operating valve and the pump are operated to perform a modulation action to absorb the shock that occurs when the pump is operated, and cavitation that occurs when the pump is operated is further prevented. 2. In order to cope with different types of work, multiple operation modulations of the operating valves are provided, and the commands of the controller that governs these are either automatic or manual depending on the work mode selected by the operator. 2. The method of controlling a working machine for a construction machine according to claim 1, wherein the control method is performed by performing the above operation modulation, thereby making it possible to use various types of the operation modulation.